In the pursuit of higher data rates,
lower latency, and higher sensing accuracies, we have no choice but to consider larger carrier frequencies, above the 24 GHz band in 5G, as this is where larger bandwidths are available [1]}. At lower frequencies, (despite intense competition) OFDM has remained the communication waveform of choice, due to its robustness to multipath, its straightforward integration with multi-antenna systems, and its high flexibility in terms of power and rate allocation [2]}. In addition, OFDM is suitable for JRC with standard FFT-processing, in both mono-static and bi-static configurations [3]}. However, at B5G frequencies, OFDM is challenged by several effects, which force us to consider alternative modulation formats: OFDM suffers from a high peak-to-average power ratio (PAPR), leading to reduced power efficiency, which becomes a limiting factor at high carriers. Secondly, OFDM require frequent adaptation due to mobility and fading, which would lead to prohibitive overheads at high carriers due to the short coherence times [2]}. Moreover, the robustness to multipath comes at a cost of inserting a cyclic prefix (CP) between OFDM symbols, resulting in a rate loss, to combat inter-symbol interference (ISI). Finally, for radar, OFDM is sensitive to inter-carrier-interference (ICI), resulting from Doppler shifts under high target velocities [5]}.
